An electricity storage device may be provided with a current interruption device that interrupts conduction when overcharge or the like occurs. This types of current interruption device is usually provided on a current path connecting an electrode assembly and a terminal. When an internal pressure of a casing exceeds a preset pressure due to overcharge or the like, the current interruption device operates to interrupt the current path. This interrupts a current flowing through the current path.
Further, the electricity storage device may include a fuse that interrupts conduction when an excessive current flows through the electricity storage device (for example, see Japanese Patent Application Publication No. H09 (1997)-17146 A). In this electricity storage device, when an excessive current flows through the electricity storage device, the fuse is heated and fused so as to interrupt the current path. This prevents the excessive current from continuing to flow through the electricity storage device.